Safety control for burner motors



J. O. DAVIS Sept. s, 1932.

SAFETY CONTROL FOR BURNER MOTORS Filed sept. 12, 195o NI/ENTOR.l

JE/7766 Q *JA/iv.

ATTORNEYS Patent-ed Sept. 6, 1932 UNITED STATES PATENT ol-FlcE AMES O. DAVIS, OF- WABASH, INDIANA, ASSIGNOR TO MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, F WABASH, INDIANA, A CORPORATION OF DELAWARE SAFETY CONTROL` FOR BURNER MOTORS Application led September 12, 1930. Serial No. 481,579.

The present application relates to safety control mechanism for oil burner installations, and among the object of the invention are to provide such a control which will be relatively simple in'construction, which`will provide for thermostatic control of the burner mechanism, which includes mechanism of such character as to preventa supply of fuel.

to the burner in case of failure of ignition, and to cut off the supply of fuel to the burner in case of failure of combustion, and which is so constructed as to provide for snap actuation of all metal to metal contact switches both in the making of contact and in the breaking thereof. The .present invention rovides novel means for operating switches of the metal to metal Contact type, and I consider this means to be br'oadly new. Further objects of the invention will appear as the description proceeds.

To the accomplishment of the above and 4related objects, `my invention may be embodied in the form illustrated in the accompanying drawing, attention being called to Z5 the fact, however, that the drawing is illustrative only and that change may be made in the specific construction illustrated and described, so long Ias the scope of the appended claims is not violated. l

In the accompanying drawing,

Fig. 1 is a diagrammatic view of mechanism constructed in accordance vention.; s

Fig. '2,A is a section through the control housing; and

Fig. 3. is aside elevation of the control housing, a portion thereof being broken away to disclose'the control elements housed there- .Referring vmore particularly to the drawino', it will be seen that the disclosed mecha' nism comprises a shaft 1() adapted to be driv- 4 en bv motor 11 and carrying-the brush arm 12 of a maintaining switch 13. Said shaft 1() further carries a plurality of cams 14, 15, 16, 17, 18, 19, 20, 21, 22 and 23, said cams being adapted, respectively, to actuate a series of contact fingers later to be described. The installation includes jalso a thermostat 60, a

5 stack switch 95,l an ignition lcoil 76, an oil with my in- 4supplying pump 84 (for which may be substituted an electrically operated valve in a gravity system), an air blower 90, and an oil burner (not shown). I f

The maintaining switch 13 comprises 'a plurality of annular, or part-annular, concentric tracks 47 49 and 55 with which cooperate, respectively, brushes 48, and 56 carried onv vthe arm 12. The maintaining switch also comprises twol diametrically spaced contact buttons 53l and 54 adapted to be contacted by the brush 50.

A choke transformer comprising a primary coil 67 and a secondary coil 69 has its primary connected in series in the circuit of theY motor 11, this transformer being so proftions of the parts,

portioned that no current Will yflow through the primary coil even though the circuit of said coil is closed; unless the secondary coil circuit is closed.

It is, of course, in any oil burner control, desirable that, under certain conditions, the

1control should attain a locked-up? condition of such character that neither the burner nor the control can be operated after the control 7i hask entered such condition Without receiving the' attention of the operator. The present control is illustrated in Fig. 1 in suchl a locked-up condition. In the illustrated posithe secondary coil 69 of choke transformer is shorted through a circuit as follows :-wire 74, track 47, ybrush48, arm A12, brush 50, track 49. wire 71, wire 70, and coil 69. A finger 40 has its upper end pivoted in the control casing 120, and the free end of said finger is alignedfor cooperation with the cam 22. A second finger 42 is similarly mounted closely adjacent the fifif ger 40, the free end of said finger l42 being positioned for actuation by the cam 23. The 90 fingern' 40 carries acontact button 41 adapted, in certain positions of said fingers 40 and 42, to contact a contact button 43 carried by the finger 42. The finger 42 has mounted thereon an arm 44 which, at its'free end, carries a con-l 95 tact button 45 adapted, in certain other positions of the fingers40 and 42, to engage a contact button 46 likewise carried by the finger 40. In the illustrated lpositions, of the parts, the contact buttons 41 and 43 are en- 'loA the l ma I gaged while the contact buttons 45 and 46 are separated. As will be readily seen, the separation ofi-the contact buttons 45 fand 46 prevents the making of a circuit through the primary coil 67 of the choke transformer for energizing the motor 11 so that, in the illustrated condition, the control is holding not only the burner, but also itself, ininactive condition.

Fingers24 and 26 are pivoted with their free ends in cooperative Y relation with the cams 14 and 15 respectively, and the finger 24 carries a contact button 25 adapted, in certain positions of said fingers, to engage a contact point 27 carried by the finger 26. Similarly, ngers 28 and 30 are positioned to be actuated by cams 16`and 17 and carry cooperative contact points 29 and 31; fingers 32 and 34 are positioned to be actuated by cams 18 and 19 respectively and carry contact buttons 33 and 35; and fingers 36 and 38 are positioned to be actuated by cams 20 and 21 and carry contact buttons 37 and 39. All of the gers are provided with spring means urging the free ends of said fingers toward contact with their respective cams. In Fig. 2, I have illustrated coil springs 122 surrounding the pivots of the lingers, one end of each spring engaging its finger and the other end thereof engaging an abutment on the carrying piece 121 upon which said lingers are mounted, but it is to be understood that any spring means having this function may be substituted for those illustrated.

Means is provided for reinitiating thev operation of the control after the same has reached the locked-up condition illustrated in Fig. 1. A contact bar 86 is provided with a push button 100, and is normally urged into the position illustrated by an expansion spring 106 or the like. If the bar 86 is moved, by pressing upon the button 100, into contact with the terminals of the wires 102 and 103, an energizing circuit for the motor 11 is established as follows power line 57, wire 63, wire 101, wire 102, bar 86, wire 103, wire 78, finger 42, contact button 43, contact button 41,

finger 40, wire 65, motor 11, wire`66, primary coil 67, wire 68, and power line 58. Since the secondary coil 69 of the choke transformer is already energized through the circuit above described, the establishment of this circuit initiates clockwise rotation of the motor 11 as viewed from the left end of Fig. 1. Almost immediately upon initiation of such rotation, the finger cam 23, and the brush with the button 54.

It is to be noted that this movement of the finger 42 which, of course, breaks the contact between the buttons 41 and 43, is an abrupt one and is effected` by the spring 122, the free end of the linger 42 dropping recipitately from the apex of the radial s oulder 105. This movement not only breaks the motor e11- 50 moves into contact 42 drops ofi the shoulder 105 of its ergizing circuit above described but also brings the contact button 45 into engagement with the button 46, thus establishing a primary motor circuit as follows power line 57, Wire 63, wirev 64, contact button 45, contact button 46, linger 40, wire 65, motor 11, wire 66, primary coil 67, wire 68, and power line 58. Simultaneously, a new circuit through the secondary coil is closed as follows z-wire 70, wire 96, mercury tube 94, wire 93, track 55, brush 56, arm 12, brush 48, track 47, wire 74, and secondary coil 69, it being understood that the previously described secondary circuit has been broof the choke transformer ken by the movement of the brush 50 olf of 89 the track 49 and onto the button 54. When these circuits have been established the button 100 may be released to permit the spring 106 to return the bar 86 to the illustrated position.

The illustrated position of the stack thermostat 95 is` the cold position. It will be appreciated, then, that if, for any reason, the

Ystack thermostatis jammed or otherwise held in its opposite position, the mercury in the tube 94 will be in the opposite end thereof, so that no circuit can be established through said tube. Under such conditions, the motor will be Contact with the button 54, and cannot again be started until the stack switch 95 is moved to the illustrated position.

Presuming, however, that the stack switch is in the illustrated position, the motor 11 .will continue to operate under the influence the brush 50 again into Contact with the track 49. As the shaft 10 vcontinues to rotate, the brush 50 drops olf the end 75 of the track 49. Again continuation` of the operation of the motor 11 becomes dependent upon the above described circuit through the mercury tube 94. Substantially simultaneously, the fingers 26 and 30 drop ofi' the shoulders 107 and 108 of their respective cams 15 and 17, separating contacts 25 and 27 and contacts 29 and 31. of the circuit through the tube 94 the motor 11 will continue to operate, bringing the brush 50 again into contact with the track 49 at the end 97 thereof to re-establish the firsttraced secondary circuit, and then almost imstopped with the brush 50 in 9b' the two last mentioned circuits, bringing Again'presuming the existence mediately carrying the brush 56 ofi' of the end 98 of the track 55 to break the maintaining circuit through the tube 94. Ultimately, the brush 50 again leaves the track 49 and engages the button 53. In this position, the secondary motor circuit is placed under the control of the thermostat 60, and the contact buttons 25-27, 29`31, and 33-35 are separated, Iwhile cam 21 has moved contact 39 carried by finger 38 into Contact with button 37 carried by linger 36, and contacts 45 and 46 are, of course, still closed.

If the arm 59 of the thermostat 60 is not lso again energizing or shorting the secondary 69 Contact in contact with the post 61, the control mechanism now comes to rest with no operative circuitsgestablished. As illustrated, however, the arm 59 is in contact with the post 61, as is always the case when the thermo.- stat is calling for heat, and consequently a new secondary circuit is established as follows z-wire 70, wire 71, track 49, wire 72, thermostat post 60, thermostat arm 59, thermostat post 61,-wire 73, button 53, brush 50, arm 12, brush 48, track 47 wire 74, and secondary coil 69. The motor 11 and primary coil 67 being energized through the previously described circuit through the contacts and 46, the motor continues the rotation of the shaft 10 and moves the brush 50 off the button 53 and onto the track 49, thus destroying the control of the thermostat and throughthe previously described circuit 1ncluding the brush andthe track 49.

As thel finger 32 drops off the' shoulder 109 of its cam 18, thus establishing contact-between the points 33 and 35 and establishing an ignition circuit as follows z-power line 57 wire 63, finger 36, contact 38, wire 77, wire 7 8, wire 79, finger 34, contact 35, contact 33, finger 32, wire 80, ignition lcoil 76, wire 81, wire 68, and power line 58.

Almost immediately thereafter, as the mot-or 11 continues to rotate,

the shoulders 110 and 111 of their respective cams 14 and 16," thus establishing between the buttons 25 and 27 and between the buttons 29 and 31. Closure of these switches establishes a circuit through the oil control 84 as follows :#power line 57, wire 63, finger 36, contact 37, contact 39, finger 38,

contact 27, contact 25, finger 24, wire 83, oil

control 84, wire 85, bar 86, wire 87, wire 81, ivire 68, and power line 58; and a circuit through the -power line 57, wire 63, finger 36, contact 37,

blower motor as follows contact 39, fingery 38, wire 77, wire 78, wire 88, finger 30, contact 31, contact 29, finger 28, wire 89, blower motor 90, wire `91wire 85, bar 86, wire 87, wire 81, wire 68, and power line 58.

Conditions are now proper for the initiation of combustion, and the motor 11 continues to rotate, holding these favorable conditions for a short time, or until a position substantially that shown in Fig. 1 is reached.

Just before this position is reached, the fingers 34, 38 and 40 drop ofi` the shoulders 1 12, 113 and 114 of their respective .cams 19, 21 and' 22; whereby the primary energizing circuit for the motor 11 is broken at 45-46;

,the ignition circuit is broken at 37-39 and at 33-35; and the temporary energizing circuits for the oil control- 84 and the blower' motor .90 are broken at 37-39. If ignition has not taken place by this time, the motor brush 50 leaves the button 53, the

button 37, button 39, fingerv time,

the fingers 24 and 28 f closed circuit through wire 77 wire 78, wire 82, finger 26,

.the room thermostat g for cold, the arm 59 thereof moving into con- `stops in the locked-up position shown in theA wire 101, tube 99, wire 78, wire 82, finger 26, contact 27, contact 25, finger 24, wire 83, oil control 84, wire 85, bar 86, wire 87 wire 81, wire 68, and power line 58; and power line 57 wire 63, wire 101, mercury tube 99, wire 7 8, wire 88, finger 30, contact 31,'contact 29,1inger 28, wire 89', blower motor 90, wire 91wire 85, bar 86, wire 87, wire 81, Wire 68, and power line 58 to continue the supply of fuel to theburner. y

A rimary motor circuit is'likewise maintained through tube 99 as follows z-power line 57, wire 63, wire 101, tube 99, wire 78, finger 42, contact 43, contact 41, fin er 40, wire 65, motor 1,1, wire 66, primary 6 n, wire 68, and power line58. Since there is, at this a secondary circuit through the secondary coil 69 of the .choke transformer as followsz-wire 70, wire 71, track 49, brush 50, arm 12, brush 48, track 47, wire 74, and secondary coil 69, the motor 11 will continue to operate until the brush 50 reaches the button54. Since the stack thermostat has `been swung to its hot position, there is no 100 the secondary coil 69 in this position of the parts, and the motor will stop. This is the normal operating tondition ofthe control.

If, for any reason, the flame should be accidently extinguished at this time, the stack thermostat would quickly cool down sufficiently to cause the element 95 toswing into the position illustrated, whereby the secondary coil 69 would be shorted as ol- 110 lows z-70--96-94-93-55-56-12-48 47-74--69, and the device willlbe'recycled in the manner above described, coming finally either to a normal operating condition or to a locked-up condition depending upon whether or not combustion is initiated, as explained above.

Assumin that the burner operates properly until t e temperature of the controlled space reaches the predetermined optimum.

will be shifted to call tact with the post 62. It being remembered thatpa closed primary motor circuit already exists, it will be seen that this shift of the arm 59 will initiate operation ofI the control motor 11 byshorting the secondary coil 69 as ollowsz-wire 70, wire 71, track 49, wire .72, postl 60, arm 59, postl 62, wire 104, button 54, brush 50, arm`12, brush 48, track 47, wire 74, and secondary coil 69. As the motor operates, the brush 50 is moved ofi' the button 54 and onto the track 49, thus breaking the above described secondary circuit and establishing another as previously traced, thus :--7l-49*50-12-48-4774-69 to continue the operation of the motor. As the brush 50 moves off the end 7 5 of the track 49, fingers 26 and 30 drop off the shoulders 107 and 108 of their respective cams 15 and 17, thus breaking the fuel-supplying circuits. As previously explained, the primary motor circuit is now through the contacts 45 and 46 and not through the contacts 43 and 41. When the brush 50 leaves the track 49, it breaks the only secondary circuit, and the control motor stops, leaving only contacts 45 and 46 closed. v

When the stack cools ofil sufficiently to permit the element to swing back to the position illustrated in the drawing the fiuid in the tube 94 will short the terminals thereof, establishing a secondary motor circuit as follows 7 0-96-9493-`-55-56-12- 48-47-74-69, and the motor will be operated through that circuit until the brush 56 leaves the track 55. Before that brush leaves its track, however, the brush 50 has re-engaged the track 49 at the end 97, to re-establish the circuit 70-71-49-50-12-48- 47-74-69, so that the motor will continue to operate until the brush 50 again rests on the button 53. In this position, the motor 11 will stop with contacts 25-27, 29-31, 33-

35, and 41-43 open; and with contacts 37-39 and 45-46 closed, awaiting another call for heat by the room thermostat.

. It will be noted that each movement of any one of the several fingers which either establishes or breaks a circuit is a sudden one effected by the springs acting on said fingers. For instance, the contacts 25 and 27 are separated when the cam 15, which has fiexed the spring controlling the finger 26, moves to permit the freek end of said finger to drop off the shoulder 107. As the cams 14 and 15 continue to rotate, the spring controlling the finger 24 is flexed, then the spring controlling the finger 26 is again flexed, and thereafter the cam 14 moves to permit the free end of the finger 24 to drop off of the shoulder 110 of said cam under the influence of the spring 122, to establish contact between the buttons 25 and 27.

Thus, with one exception, each relative movement between the fingers of any pair occurs as the result of the controlling cam for one of said fingers permitting its finger to drop off a precipitate shoulder, and this is true whether the movement effects separation or contact of the buttons carried by said fingers. The one exception mentioned is in the movement whereby the buttons 37 and 39 are brought into contact, it being noted that the `with said second finger, ,second finger to drop,

cam 20 is truly circular, and that the cam 21 brings the finger 38 gradually into position to effect contact between the buttons 37 and 39. It will be noted that the buttons 37 and 39 are never brought into contact at a time with the primary motor Acircuit through the buttons 45 and 46.

I claim as my invention:

1. Switch mechanism comprising a finger, a second finger mounted for cooperation with said first finger and adapted to contact one -face thereof, resilient means biasing said fingers against movement in one direction, a Contact member movable with, but insulated from, said second finger and adapted to contact the opposite face of said first finger, and means for flexingsaid resilient means and permitting said first finger to drop, under the infiuence of said resilient means, into cont-act and permitting said under the influence of said resilient means, to break the contact between said first finger andsaid second finger and to make contact between said contact member and said first finger.

2. Switch mechanism comprising a finger, a second finger mounted for cooperation with said first finger and adapted to contact one face thereof, resilient means biasing said fingers against movement in one direction, a contact member movable with, but insulated from, said second finger and adapted to contact the opposite face of said rst finger, a

shaft, a cam fast on said shaft and engaging said first finger, a second cam fast on said shaft and engaging said second fin er, and means for rotating said shaft, said rst cam being formed with a portion concentric with said shaft on aradius such as to move said first finger against its bias, and with a portion of materially less radius, said portions being separated by an abrupt shoulder, and said second cam being formed with a portion concentric with Said shaft on a radius such as to mov said second finger against its bias and substantially coextensive with said first-mentioned portion of said first cam, and with a portion of materially less radius, said portions of said second cam being separated by an abrupt shoulder, peripherally spaced from the shoulder of said first cam.

3. Switch mechanism comprising a finger..

lIO

and adapted to contact the opposite face of said first finger, said fingers and said member being resiliently biased against movement in one direction, operating means associated with said first finger, and operating means associated with said second finger, said means being operable to eiect abrupt making and breaking of Contact between said first finger and said second finger and between said first finger and said contact member.

4. Switch mechanism comprising affinger, a second finger mounted for cooperation with said first finger and adapted to contact one face thereof, a contact member associated with, but insulatedY from, said second finger and adapted to contact the opposite face of said first finger, said fingers and said member being resiliently biased against movement in one direction, and means for moving said fingers against the influence of their bias and subsequent-1y permitting said first finger to move abruptly, under the influence of its bias, into Contact with said second finger, and subsequently permitting said second finger to move abruptly, under the infiuenceof its bias to break such contact and to make Contact between said first finger and said contact member.

In witness whereof, I have hereunto set my hand at Wabash, Indiana, this 9th day of September, A. D. one thousand nine hundred and thirty. J S O DAX-TIS 

